Question

Two equal positive point charges are separated by a distance $2a$. The distance of a point from the centre of the line joining two charges on the equatorial line (perpendicular bisector) at which force experienced by a test charge $q_0$ becomes maximum is $\frac{a}{\sqrt{x}}$. The value of $x$ is ______

Answer 1

Answer: 2

$F=\frac{2Kq{q}_{0}x}{{\left(x^2+a^2\right)}^{3/2}}$
For $F$ to be maximum
$\frac{dF}{dx}=0$
$x=\frac{a}{\sqrt{2}}$